Ultrasonic phased-array transducers comprise a number of transducer elements arranged along an azimuth axis that are used to transmit and receive ultrasonic energy. Typically, individual transducer elements are formed by dicing a monolithic piece of piezoelectric material. In one manufacturing approach, one side of a matching layer is bonded to a monolithic piece of piezoelectric material, and another side of the matching layer is temporally bonded onto a platen, which provides support to the assembly during the dicing operation. In this approach, a dicing saw cuts through the piezoelectric material, through the matching layers, and into the platen. Then, the kerfs formed by the dicing operation are filled, electrical connections are made to the individual elements, and a backing is cast onto the diced piezoelectric material. The platen is then removed from the matching layers, and an acoustic window (typically, a soft RTV rubber or urethane lens) is applied over the matching layers. One disadvantage to this approach is the difficulty and labor associated with removing the platen.
In another manufacturing approach, a flex circuit is disposed on the piezoelectric material to provide positive electrical connection to each transducer element, and the piezoelectric material is bonded to a solid backer with the flex circuit sandwiched between the piezoelectric material and the backer. The matching layers are then bonded to the piezoelectric material with a sandwiched foil layer used as a ground connection. A dicing saw cuts from the patient side of the assembly through the matching layers, through the piezoelectric material, and into the solid backer. In this way, the undiced portion of the solid backer holds the diced assembly together. After the dicing operation, an acoustic window is applied over the matching layers. Because the solid backer supports the assembly during the dicing operation and is part of the final transducer device, the solid backer does not need to be removed, unlike the platen in the approach described above.
In yet another approach, two matching layers are cast onto the piezoelectric material and ground to a desired thickness. Either the piezoelectric material only or the piezoelectric material and one (but not both) of the matching layers is diced from the backing side. Then, an acoustic window is applied over the matching layers, positive and negative electrical connections are made on the backing side of the ceramic, and a backer is cast in place. Because both matching layers are not diced in this approach, the resulting transducer may not have an optimal off-axis response since the individual elements are not completely isolated.
There is a need, therefore, for an ultrasound transducer and method of manufacture thereof that overcome the disadvantages described above.
The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims.
By way of introduction, the preferred embodiments described below provide an improved ultrasound transducer and method of manufacture thereof. In one preferred embodiment, a method of manufacturing an ultrasound transducer is provided comprising the acts of supporting a layer of piezoelectric material with a window and separating the layer of piezoelectric material into at least two elements by dicing through the layer of piezoelectric material and at least partially into the window. In another preferred embodiment, an ultrasound transducer is provided comprising a first transducer element, a second transducer element, and a window coupled with the first and second transducer elements and comprising a kerf positioned between the first and second transducer elements.
The preferred embodiments will now be described with reference to the attached drawings.